That has almost no strength at all. The bending direction from the left to right of the car is basically nothing. I can bend 1/4" bar by hand without heating it. You need a 3D shape.
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This is very stuff. It's made of similar materials but it controls flex and bending in both directions. Shouldn't be terribly hard to do it right. It's especially important since that's the crossmember the torsion bars are connected to.
The lower crossmember should be strong also, but I wouldn't rely on just that.
Been 6 years with the setup on my car but the car was stiff other than the edges of the floors as soon as that upper crossmember was in.